PIAS proteins promote SUMO-1 conjugation to STAT1

Department of Chemistry, University of Helsinki, Helsinki, Uusimaa, Finland
Blood (Impact Factor: 10.45). 12/2003; 102(9):3311-3. DOI: 10.1182/blood-2002-12-3816
Source: PubMed


Signal transducer and activator of transcription 1 (STAT1) is a critical mediator of interferon-gamma (IFN-gamma)-induced transcription that is regulated through posttranslational modifications and through transacting proteins such as protein inhibitor of activated STAT1 (PIAS1). PIAS proteins have been shown to function as E3-type small ubiquitin-like modifier (SUMO) ligases, and sumoylation has been identified as a modulatory mechanism for several transcription factors. Here we show that STAT1 is subject to SUMO-1 modification, and sumoylation occurs in vivo and in vitro at a single, evolutionary conserved amino acid residue Lys703. Members of the PIAS family of proteins were found to strongly stimulate sumoylation of STAT1. Furthermore, activation of STAT1 by IFN-gamma or pervanadate induced SUMO-1 conjugation. Mutation of Lys703 in STAT1 resulted in increased IFN-gamma-mediated transactivation, suggesting a negative regulatory function for sumoylation. These results indicate that STAT1 is covalently modified by SUMO-1 in cytokine signaling and that PIAS proteins promote SUMO-1 conjugation to STAT1.

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Available from: Olli A Jänne, Feb 28, 2014
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    • "STAT1 WT-HA, STAT1 WT-Flag, STAT1 K703R-HA, STAT1 E705A-HA and STAT1 Y701F plasmids were previously described [11-13]. STAT1 E705Q mutation was created with site directed polymerase chain reaction (PCR) mutagenesis using primers: 5’-GGAACTGGATATATCAAGACTCAGTTGATTTCTGTGTC-3’ and 5’-GACACAGAAATCAACTGAGTCTTGATATATCCAGTTCC-3’. "
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    ABSTRACT: Background STAT1 is an essential transcription factor for interferon-γ-mediated gene responses. A distinct sumoylation consensus site (ψKxE) 702IKTE705 is localized in the C-terminal region of STAT1, where Lys703 is a target for PIAS-induced SUMO modification. Several studies indicate that sumoylation has an inhibitory role on STAT1-mediated gene expression but the molecular mechanisms are not fully understood. Results Here, we have performed a structural and functional analysis of sumoylation in STAT1. We show that deconjugation of SUMO by SENP1 enhances the transcriptional activity of STAT1, confirming a negative regulatory effect of sumoylation on STAT1 activity. Inspection of molecular model indicated that consensus site is well exposed to SUMO-conjugation in STAT1 homodimer and that the conjugated SUMO moiety is directed towards DNA, thus able to form a sterical hindrance affecting promoter binding of dimeric STAT1. In addition, oligoprecipitation experiments indicated that sumoylation deficient STAT1 E705Q mutant has higher DNA-binding activity on STAT1 responsive gene promoters than wild-type STAT1. Furthermore, sumoylation deficient STAT1 E705Q mutant displayed enhanced histone H4 acetylation on interferon-γ-responsive promoter compared to wild-type STAT1. Conclusions Our results suggest that sumoylation participates in regulation of STAT1 responses by modulating DNA-binding properties of STAT1.
    BMC Biochemistry 10/2012; 13(1):20. DOI:10.1186/1471-2091-13-20 · 1.44 Impact Factor
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    • "Compared with SUMOylation of wild-type STAT5, SUMOylation of single mutants or combined mutants remained unchanged, suggesting that these lysine residues are not involved in SUMOylation of STAT5 (Figure S6A). Previous studies indicate that STAT1 is SUMOylated at lysine 703, close to tyrosine 701 (Rogers et al., 2003; Song et al., 2006; Ungureanu et al., 2003). Indeed, STAT5A contains two lysines at 696 and 700, close to tyrosine 694 (Figure 5A). "
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    ABSTRACT: Small ubiquitin-like modifier (SUMO) modification has emerged as an important regulatory mechanism during embryonic development. However, it is not known whether SUMOylation plays a role in the development of the immune system. Here, we show that SUMO-specific protease 1 (SENP1) is essential for the development of early T and B cells. STAT5, a key regulator of lymphoid development, is modified by SUMO-2 and is specifically regulated by SENP1. In the absence of SENP1, SUMO-2 modified STAT5 accumulates in early lymphoid precursors, resulting in a block in its acetylation and subsequent signaling. These results demonstrate a crucial role of SENP1 in the regulation of STAT5 activation during early lymphoid development.
    Molecular cell 01/2012; 45(2):210-21. DOI:10.1016/j.molcel.2011.12.026 · 14.02 Impact Factor
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    • "The Drosophila protein inhibitor of activated STAT (dPIAS) is homologous to the mammalian PIAS proteins (Hari et al., 2001), which inhibit STAT signaling by promoting STAT degradation (Chung et al., 1997; Liu et al., 1998; Ungureanu et al., 2003). Overexpression of dPIAS decreases eye size, and down-regulation of dPIAS partially suppresses the small-eye phenotype of the upd loss-of-function mutant, os1, suggesting that dPIAS is a negative regulator of the JAK/STAT signaling pathway (Betz et al., 2001). "
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    ABSTRACT: The Janus kinase (JAK) signal transducer and activator of transcription (STAT) pathway is one of the main signaling pathways in eukaryotic cells. This pathway is used during diverse growth and developmental processes in multiple tissues to control cell proliferation, differentiation, survival, and apoptosis. In addition to its role during development, the JAK/STAT pathway has also been implicated in tumorigenesis. Drosophila melanogaster is a powerful genetic tool, and its eyes have been used extensively as a platform to study signaling pathways. Many reports have demonstrated that the JAK/STAT pathway plays pleiotropic roles in Drosophila eye development. Its functions and activation are decided by its interplay with other signal pathways and the epigenetic status. In this review, we focus on the functions and regulation of the JAK/STAT pathway during eye development and provide some insights into the study of this pathway in tumorigenesis.
    Developmental Dynamics 10/2010; 239(10):2522-33. DOI:10.1002/dvdy.22394 · 2.38 Impact Factor
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